yaml safe_load of many different objects - deserialization

Question

I have a huge YAML file with tag definitions like in this snippet
- !!python/object:manufacturer.Manufacturer
name: aaaa
address: !!python/object:address.BusinessAddress {street: bbbb, number: 123, city: cccc}
And I needed to load this, first to make sure that the file is correct YAML, second to extract information at a certain tree-dept given a certain context. I had this all as nested dicts, lists and primitives that would be straightforward to do. But I cannot load the file as I don't have the original Python sources and class defines, so yaml.load() is out.
I have tried yaml.safe_load() but that throws and exception.
The BaseLoader loads the file, so it is correct. But that jumbles all primitive information (number, datetime) together as strings.
Then I found How to deserialize an object with PyYAML using safe_load?, since the file has over 100 different tags defined, the solutions presented there is impractical.
Do I have to use some other tools to strip the !!tag definitions (there is at least one occasion where !! occurs inside a normal string), so I can use safe_load. Is there simpler way to do solve this that I am not aware of?
If not I will have to do some string parsing to get the types back, but I thought I ask here first.

Answer 1

There is no need to go the cumbersome route of adding any of the classes if you want to use the safe_loader() on such a file.
You should have gotten an ConstructorError thrown in SafeConstructor.construct_undefined() in constructor.py. That method gets registered for the fall through case 'None' in the constructor.py file.
If you combine that info with the fact that all such tagged "classes" are mappings (and not lists or scalars), you can just copy the code for the mappings in a new function and register that as the fall-through case.
import yaml
from yaml.constructor import SafeConstructor
def my_construct_undefined(self, node):
data = {}
yield data
value = self.construct_mapping(node)
data.update(value)
SafeConstructor.add_constructor(
None, my_construct_undefined)
yaml_str = """\
- !!python/object:manufacturer.Manufacturer
name: aaaa
address: !!python/object:address.BusinessAddress {street: bbbb, number: 123, city: cccc}
"""
data = yaml.safe_load(yaml_str)
print(data)
should get you:
[{'name': 'aaaa', 'address': {'city': 'cccc', 'street': 'bbbb', 'number': 123}}]
without an exception thrown, and with "number" as integer not as string.